Field of the Invention
The present invention relate to a method for removing aquatic organic matters from water, and particularly, to a method and a reactor for removing aquatic organic matters synergistically by combining an immobilized peroxidase on electrode with electro-coagulation in a single electrochemical system.
Background Information
With the rapid industrialization in China, effluents discharged from industrial wastewater still contain a great quantity and variety of dissolved organic matters at a low concentration and with complicated constitution. For example, some effluents discharged directly after biochemical treatment still contain organic matters at a low concentration, e.g., polyphenols, polycyclic aromatic hydrocarbons, heterocyclic compounds, large molecular humic substances, etc. As a result, organic pollutants with low concentrations in water are increasingly serious in recent years and become an important hidden danger in water safety.
Enzymatic catalysis technology is a new-developed water treatment technology. On one hand, the enzymatic catalysis process has the advantages of a high catalytic activity, a rapid reaction rate, a high selectivity for the pollutants at a lower concentration, mild reaction conditions, simple and convenient treatment process, etc. On the other hand, a prominent merit of the electrochemical method is that the reaction speed can be controlled easily by the voltage and current without involving any additives and thus it owns a clean process. Accordingly, direct immobilization of enzyme molecules onto the surface of the electrode for direct electrochemical reaction has been got a great attention in water and wastewater treatments. Studies show that, when a peroxidase is immobilized on the surface of a cathode, the enzyme molecule still has high catalytic activity for polymerization on phenolic and aniline pollutants and accordingly form insoluble polymerization products for further precipitation and removal. However, this electro-enzymatic catalysis technology encounters the following limitations in practice: (1) addition amount of enzyme is high and thus the cost is increased; (2) precipitation and removal of the catalytic polymerization products are insufficient; (3) the anode is underutilized and thus leads to waste of energy; and (4) there is a limited effect on the removal of organic matters.
It is proved that the electro-coagulation technology has a greater advantage on improving the efficiency of water and wastewater treatments than the conventional coagulation process, and thus, it is widely used in the field of water and wastewater treatments. The electro-coagulation process has not only a good effect on removing effectively suspended substances in water and accordingly reducing the turbidity and chromaticity but also a better removal effect on organic matters, heavy metals and microbes in water, especially suitable for a small-scale water treatment. Generally, the basic principle of the electro-coagulation where an aluminum plate acts as the anode is that: placing an aluminum electrode in a raw water to be treated and applying a direct current to it such that the anode performs an electrochemical reaction and dissolves aluminum ions, after being performed hydrolysis, polymerization and complexing reactions under certain conditions, the aluminum ions then form a series of in situ polymerized aluminum hydrolyzed products and aluminum hydroxide precipitations with different charge quantities on the surfaces thereof. The electro-coagulation technology and the chemical coagulation technology are basically of the same nature, that is, they both function to remove the colloids and the suspended substances from water through coagulation/flocculation. However, the fresh polymerized aluminum hydrolyzed products generated in-situ during the electro-coagulation process has a relatively high reaction activity, which reduces the required amount of aluminum to a great extent and thus the consumption amount of aluminum in the electro-coagulation is about one third of that in the chemical coagulation method. However, the electro-coagulation technology also has the following disadvantages: (1) bad selectivity for the low-concentration pollutants; (2) poor effect in removing small-molecular hydrophilic organic matters; and (3) underutilization of the cathode which results in waste of energy.